The invention pertains to so-called 3GPP (third generation partnership program) IMS (Internet Protocol Multimedia Subsystem) services, and more particularly to signaling to provide such services at an appropriate QoS level (quality of service).
Today, via the Internet, two terminals (e.g. two PCs) can communicate voice, video and data and not only via strictly a wireline network, but also via a telecommunication system in which at least part of the communication path is wireless, and includes a radio access network (RAN), such as the RAN providing access to UMTS (Universal Mobile Telecommunications System) being developed under the auspices of 3GPP (Third Generation Partnership Program). To enable such multimedia (MM) communication between two terminals, the UMTS includes a component referred to as IMS (Internet Protocol Multimedia Subsystem).
The 3GPP system (UMTS) in its first release (R99) was designed to be backward compatible with the existing GSM (Global System for Mobile Communications) circuit switched infrastructure. As the costs to procure and maintain the very proprietary hardware of circuit switched systems are very high, and much of the bandwidth used to transmit user data is lost, the 3GPP system is slowly evolving toward an all-IP core network, and so the existing circuit switched infrastructure will ultimately be outdated and replaced by IP-based hardware, which is open, scalable, and cheaper to procure and maintain due to a more competitive market. Thus, through REL-4 and REL-5 of the 3GPP specifications, more and more importance is given to IP-based architecture, and the IMS is introduced, firstly to handle classical circuit switched services (like voice) over IP (VoIP), secondly to handle all multimedia services provided to subscribers.
As shown in FIG. 1A, the IMS (IP Multimedia Subsystem) is an extension of the PS (packet-switched) Core Network (CN) of UMTS, intended to become independent of the PS-CN from REL-6 on. It uses the Session Initiation Protocol (SIP) to set up, maintain and terminate voice and multimedia sessions. An example of such a session is a series of communications in which a user is first engaged in a voice communication, and then receives an incoming IP video communication, but decides not to accept the communication, and instead diverts the incoming video to a messaging system (which then posts in the user""s mail box a message indicating that the user has new mail, i.e. the video message).
SIP is a part of the overall Internet Engineering Task Force (IETF) multimedia data and control architecture. It is used in conjunction with other IETF protocols, such as the Session Description Protocol (SDP) and the Real-Time Protocol (RTP). SIP is a signaling protocol for handling the setup, modification, and teardown of MM sessions, and in combination with the protocols with which it is used, describes the session characteristics of a communication session to potential session participants. Usually, RTP is used to exchange the media (audio, voice or data) during the communication session, but SIP allows any transport protocol to be used. Also, usually, the SIP messages (signaling) pass through some of the same equipment as the media to be exchanged during a communication session, but it is important to maintain a logical separation between SIP signaling and the communication of the media (the session data), because the SIP signaling for a communication session might pass through one or more proxy servers while the media stream uses a more direct path between the participants in the communication session.
As also shown in FIG. 1A (and also in FIG. 1B), because of the services provided by IMS 12c included in the CN PS domain 12b, and as already indicated above, a PC/TE 11a coupled to UMTS via a MT (mobile terminal) 11b can communicate voice, video and data with another PC 14 connected to the Internet 15. The PC/TE 11a can communicate with the MT 11b in any of various ways, including for example using Bluetooth (BT). In such a communication, the PC/TE 11a and the MT 11b, so coupled, in combination make up what is called user equipment (UE). In general, a UE device is an MT coupled to a terminal equipment (TE) device such as, but not necessarily restricted to a PC; a UE device can be an IMS-enabled mobile phone, including a MT coupled to a TE device that is a specialized processor, not what is generally referred to as a PC. But it should be realized that these are logical entities that can be combined in a single physical device.
When using IMS, user identification is based on a unique private identity, used only by the UE and the core network, an identity comparable in function to the IMSI (International Mobile Subscriber Identity) and also based on public identities used by third parties to address a user (and typically written on business cards and the like). Authentication uses the principles of UMTS AKA (authentication and key agreement), the 3GPP authentication scheme. The authentication for IMS is separated from UMTS authentication and the secret keys and functions for IMS usage are independent from the secret keys and functions used in the UMTS subscription (also needed to access IMS), but can be the same. The idea is that a UE starts a MM communication via IMS by establishing a PDP (packet data protocol) context with GGSN via SGSN, and so is identified and authenticated in the PS domain before it identifies and authenticates in the IMS domain. When IMS becomes access independent as planned, one will be able to think of a UE connecting to IMS via a WLAN (wireless local area network) or a fixed LAN, thus requiring specific access credentials for the access network, while gaining access to IMS services by satisfying IMS-specific authentication requirements.
The IMS protocols used to set up a data flow between a UE device (including a PC/TE) and an IMS server are IPv6 (Internet Protocol version 6) and the above-mentioned SIP, and more specifically, SIP with SDP. For IMS, SIP includes extensions not found in the earlier, original SIP, per the IETF RFC (request for comments) 2543 nor found in the new updated version of SIP RFC 3261. According to the MT-TE split now being considered, there is a UA (user agent) in the TE (e.g. a PC) that knows SIP without all extensions and improvements required for IMS clients, and the TE is able to use 3GPP IMS services transparently. Since IMS services include RT (Real time) a data flows (voice, video, or data) it requires QoS support from the underlying network. The QoS has to be set up end-to-end so that the user will experience the QoS subscribed to and paid for. The SIP extensions allow for providing such QoS, among other services, such as security. (With a split TE-MT arrangement, a TE can use more than one data flow and with different QoS characteristics at a time, there being a PDP context for each data flow, and the QoS characteristics for each data flow, including the local connection between MT and TE, can be set separately.)
If the SIP extensions providing IMS SIP are implemented in the UA of the TE, then the UA ends up being more intelligent (i.e. xe2x80x9cknowsxe2x80x9d more signaling) and so more complex than is necessary in many circumstances (where IMS services are not being invoked, i.e. in circumstances where the MT is not functioning as an IP router, classifying each IP packet and putting it in an appropriate PDP context).
What is needed is a way to implement (i.e. to provide for a way to respond to) SIP extensions without making the UA unnecessarily complex.
Accordingly, the present invention provides a user equipment (UE) device including a mobile terminal (MT) coupled to a terminal equipment (TE) device, for use in multimedia communication requests for internet protocol (IP) communications across a packet switched communication network where the multimedia communication requests are made using signaling according to a predetermined protocol, the TE including a user agent for providing a communication establishment message as part of the signaling and including a session description protocol (SDP) component, the UE device characterized by: an IMS proxy adjunct, located in the TE device, responsive to the communication establishment message and other messages including the SDP component, for making extensions to the communication establishment message and other messages by extending the SDP component so as to reserve resources ensuring a predetermined quality of service (QoS) for the IP communications, and for originating and terminating messages according to the predetermined protocol on behalf of the user agent in the TE device so that the packet switched communication network need not take into account the operation of the IMS proxy adjunct; and an IP router and QoS manager, located in the MT, responsive to control signals provided by the IMS proxy adjunct, for providing QoS using access network specific procedures to open QoS enabled IP flows, and routing IP packets to different QoS enabled IP flows.
In accord with the first aspect of the invention, the IMS proxy adjunct may configure the local media used between MT and TE according to a required QoS level.
Also in accord with the first aspect of the invention, the IMS proxy adjunct may extend the signaling, in addition to by adding extensions to the communication establishment message and other messages, by also modifying headers, extending the SDP component, originating requests and providing responses on behalf of the terminal equipment (TE) device for any IMS required functionality.
Still also in accord with the first aspect of the invention, the MT may also include an IMS proxy (as opposed to the IMS proxy adjunct in the TE), responsive to the communication establishment message with the extended SDP, for providing a finalized communication establishment message with the extended SDP to the packet switched communication network via a radio access network, and for managing the QoS of the packet switched communication network for multimedia communication data flows. Also, the IMS proxy adjunct may also respond to messages used in a communication establishment sequence provided by the packet switched communication network via the IMS proxy or provided directly from the packet switched communication network by removing extensions from the SDP and providing the communication establishment messages without any extensions. Also still, the predetermined protocol may be the session initiation protocol (SIP) and the MT may be operative according to a procedure for registering with an Internet Protocol (IP) Multimedia Subsystem (IMS) server so as to allow the MT to access, over a digital communication system, an IP multimedia service to which the MT is subscribed, the procedure including having the MT send an SIP register message to a proxy call session control function (P-CSCF), and the SIP register message sent according to the procedure may include a field conveying information indicating whether the MT includes IMS proxy functionality; further still, in a registration coming from the TE, the IMS proxy in the MT may add a field conveying addressing information so that the IMS server is able to route subsequent SIP signaling through the IMS proxy.
In a second aspect of the invention, a method is provided by which the UE device according to the first aspect of the invention is operative.